Phalangeal head plate

ABSTRACT

A bone plate sized and shaped for fixation to a phalangeal bone includes a head extending from a first end to a second end and having first, second and third fixation element holes extending therethrough and arranged in a triangular configuration on the head, an outer wall of the head having a triangular shape corresponding to the triangular configuration, a bone contacting surface of the head being contoured to conform to the anatomy of a lateral surface of a phalangeal head and a shaft extending from the head, the shaft including fourth and fifth plate holes separated from one another by an elongated fixation element hole elongated in a direction parallel to a longitudinal axis of the shaft.

FIELD OF THE INVENTION

The present invention generally relates to bone plates for the fixationof fractures of the hand and methods of coupling these plates to bone.

BACKGROUND

Current systems and methods for the fixation of fractures are limited inthe placement and orientation of plates over the bone. For example, manyof these plates are limited to a dorsal placement over a target bonepreventing a surgeon from selecting a location optimized for thefracture.

SUMMARY OF THE INVENTION

The present invention is directed to a bone plate sized and shaped forfixation to a phalangeal bone, the bone plate comprising a headextending from a first end to a second end and having first, second andthird fixation element holes extending therethrough and arranged in atriangular configuration on the head, an outer wall of the head having atriangular shape corresponding to the triangular configuration, a bonecontacting surface of the head being contoured to conform to the anatomyof a lateral surface of a phalangeal head. The bone plate furthercomprises a shaft extending from the head, the shaft including fourthand fifth plate holes separated from one another by an elongatedfixation element hole elongated in a direction parallel to alongitudinal axis of the shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments of the invention will be described in the followingby way of example and with reference to the accompanying drawings inwhich:

FIG. 1 shows a first perspective view of a bone fixation plate accordingto a first exemplary embodiment of the invention;

FIG. 2 shows a second perspective view of the bone fixation plate ofFIG. 1;

FIG. 3 shows a third perspective view of the bone fixation plate of FIG.1;

FIG. 4 shows a cross-section of the bone fixation plate of FIG. 1 takenalong the line 4-4 and depicted without the plate hole intersecting theline 4-4 for clarity;

FIG. 5 shows a cross-section of the bone fixation plate of FIG. 1 takenalong a central longitudinal axis thereof;

FIG. 6 shows a perspective view of a bone-contacting surface of a headof the bone fixation plate of FIG. 1;

FIG. 7 depicts a first perspective view of the bone fixation plate ofFIG. 1 over a bone;

FIG. 8 depicts a second perspective view of the bone fixation plate ofFIG. 1 over a bone;

FIG. 9 depicts a third perspective view of the bone fixation plate ofFIG. 1 over a bone;

FIG. 10 depicts a fourth perspective view of the bone fixation plate ofFIG. 1 over a bone;

FIG. 11 shows a bone plate according to another embodiment of theinvention;

FIG. 12 shows a first perspective view of a bone plate according to yetanother embodiment of the invention;

FIG. 13 shows a second perspective view of the bone plate of FIG. 12;and

FIG. 14 shows a bone plate according to another embodiment of theinvention.

DETAILED DESCRIPTION

The exemplary embodiments may be further understood with reference tothe following description and the appended drawings, wherein likeelements are referred to with the same reference numerals. The exemplaryembodiments relate to apparatus and methods for the treatment offractures and, in particular, to devices for fixing fractures of thephalanges. More specifically, the exemplary bone fixation plates may beused for the fixation of uni- and bi-condylateral fractures of themiddle and proximal phalangeal head. Exemplary embodiments describe abone fixation plate having a head at a first end with an elongated shaftextending therefrom to a second end. The head of the exemplary boneplate is generally triangular with first, second and third side wallsangled relative to one another to form a triangular outer profile. Thehead of this exemplary plate includes first, second and third variableangle fixation holes positioned adjacent corners of the triangleenclosed by the head. The shaft includes an elongated hole extendingalong a hole axis parallel to a longitudinal axis of the bone plate. Aswill be described in greater detail later on, the elongated hole aids inpositioning the bone plate over a target portion of the bone. The shaftfurther comprises first and second variable angle locking holes oneither side of the elongated hole, the first and second variable angleholes being offset from the longitudinal axis of the bone plate, as willalso be described in greater detail later on. A plurality of notches isdistributed over the outer border of the bone plate. A first notchlocated at the first end of the head between first and second variableangle holes is sized and shaped to receive a collateral ligament whenthe plate is positioned over a phalanx head of a metacarpal reducinginterference from the plate with surrounding ligaments and tissues. Abone contacting surface of the head has a curvature selected to conformto a curvature of a lateral wall of proximal phalanx head to ensureflush seating of the plate thereover. As will be described in greaterdetail later on, the exemplary shape, size and contour of the exemplarybone plate permits the bone plate to be positioned along a lateral wallof metacarpal and further permits the bone plate to be positionedfurther dorsally on the metacarpal than currently available plates. Itshould be noted that the terms “proximal” and “distal” as used herein,refer to a direction toward (proximal) and away from (distal) a core ofthe body. For example, a direction from the hand to the elbow isproximal while a direction from the elbow to the hand is distal.Furthermore, when using these terms in reference to a plate to beattached to a bone, proximal will refer to a direction along the platewhen it is attached to a target bone in a desired orientation.

As shown in FIGS. 1-10, an exemplary bone plate 100 has a head 104 at afirst end 102 thereof and a shaft extending therefrom along a centrallongitudinal axis 110 to a second end 106. The head 102 is substantiallytriangular and includes first, second and third variable angle plateholes 112, 114, 116 extending therethrough from a bone contactingsurface 118 to an upper surface 120. Trajectories for the plate holeaxes 113, 115, 117 are selected to capture common fracture patternswhile avoiding the articular surface of the bone and minimizinginterference with adjacent collateral ligaments. For example, computedtomography scan data may be used to select trajectories for these holeaxes 113, 115, 117 optimized to suit the most commonly encounteredanatomy of the target portion of bone while the variable angle featureof the plate holes 112, 114, 116 permits a surgeon to vary the angle atwhich screws are inserted through these holes (relative to the holeaxes) to optimize these trajectories to suit the anatomy of a particularpatient.

The triangular configuration of the head 104 is selected to permit thebone plate 100 to be seated closer to a head of a target bone thanpossible with conventional plates. Specifically, a first corner 122 ofthe triangular head 104 is located at a proximal most end 102 of thebone plate 100. Thus, the diameter of the head 104 is smallest at theproximal most end 102, increasing to a maximum diameter at a secondcorner 124 of the triangular head. As those of skill in the art willunderstand, the reduced diameter at the first corner 122 permits thebone plate 100 to be seated closer to or on a head of the target bonethan would be possible with a bone with a larger profile. As shown inFIGS. 3, 6 and 7, a predetermined portion 103 of the head 104 at thefirst corner 122 may be curved downward toward a palmar surface of thebone in an implanted configuration. Specifically, the portion 103 may becurved toward the bone 10 so that a bone-contacting surface thereof hasa first curvature R1 with a radius of curvature of 3 mm. It is notedthat this value is exemplary only and that other dimensions areenvisioned within the scope of the invention. In another embodiment, theradius of curvature R1 may be 1-4 mm. This downward curvature aids inreduction of the fracture.

As shown in FIGS. 6 and 7, a predetermined portion 107 of the head 104at the second corner 124 may also be curved downward toward the bone ina direction toward a palmar surface of the bone in an implantedconfiguration. Specifically, the portion 107 may be curved toward thebone 10 so that a bone-contacting surface thereof has a second curvatureR2 with a radius of curvature of 5 mm. It is noted that this value isexemplary only and that other dimensions are envisioned within the scopeof the invention. In another embodiment, the radius of curvature R2 maybe 3-6 mm. This downward curvature aids in reduction of the fracture.

A curvature of the bone-contacting surface 118 is selected to conform tothe curvature of the lateral aspect of the proximal phalangeal head andto ensure a flush fit therewith. In one embodiment, the bone-contactingsurface 118 of the head 104 includes curvatures of varying radii. Asshown in FIGS. 3-10, the bone-contacting surface 118 includes aplurality of curvatures of varying radii along a length thereof, thecurvatures being selected to conform to the curvature of a bone 10.Specifically, a bone-contacting surface 118 of the head 104 includes athird curvature R3 having a radius of curvature of 6-12 mm. It is notedthat this value is exemplary only and that other dimensions areenvisioned within the scope of the invention. The radius of curvature R3is centered about the first plate hole 112 and extends parallel to thecentral longitudinal axis 110. In another embodiment, the thirdcurvature R3 may be offset relative to the central longitudinal axis110. FIG. 4 depicts a cross-section of the bone plate 100 taken alongthe line 2-2 and depicted without the second plate hole 114 for clarity.As shown in FIG. 4, the third curvature R3 is defined by an arc of acylinder positioned against the bone plate 100 and extending along anaxis parallel or offset with respect to the axis 116.

The head 104 includes a first notch 140 at the proximal end 102 betweenthe first and second plate holes 112, 114. The notch 140 has asubstantially rounded shape and is offset from the longitudinal axis110. In an exemplary embodiment, a shape of the notch 140 corresponds toan arc of a circle. In one embodiment, the notch 140 has a third radiusof curvature of 0.7 mm. However, this radius of curvature is exemplaryonly and other values may be used without deviating from the scope ofthe invention. The notch 140 is positioned to receive a guide-wire (notshown) inserted in a condyle of a target bone, as will be described ingreater detail with respect to the exemplary method below. Furthermore,the notch 140 is sized to accommodate the collateral ligament thereinwhen positioned in a target orientation over the bone. In anotherembodiment, the notch 140 may have a non-circular shape (e.g., oblong,etc.) without deviating from the scope of the invention.

The head 104 further comprises a second notch 142 between the first andthird plate holes 112, 116. The notch 142 is formed as a cutoutextending into the first lateral wall 132 and having an oblong shape. Athird notch 144 extends into the head 104 along a second lateral wall134 of the bone plate 100. The first, second and third notches 140, 142,144 reduce an outer profile of the bone plate 100 without compromisingthe structural integrity thereof. The bone-contacting surface of thehead 104 at the second notch 142 is curved with a fourth curvature R4having a radius of curvature of 3-6 mm, as shown in FIG. 10.

A reduced diameter neck 105 separates the head 104 from the shaft 108.The shaft 108 extends distally from the neck 105 to the distal end 106and includes fourth and fifth variable angle plate holes 126, 128. Inone embodiment, a trajectory 127 of the fourth plate hole 126 isoriented to extend toward a first lateral wall 132 of the bone plate 100from the upper surface 120 to the bone contacting surface 118. Atrajectory 129 of the fifth plate hole 128 may be different than thetrajectory 127. In a preferred embodiment, trajectories 113, 115, 117are angled toward a center of the target bone and trajectories 113, 115,117 are angled to diverge from one another. It is noted, however, thatthese trajectories are exemplary only and any other orientation of thetrajectories 113, 115, 117, 127, 129 may be employed in an alternateembodiment. The trajectories 127, 129 may assume any path selected tolockingly engage the bone without extending through an opposing corticalsurface thereof. The shaft 108 also includes an elongated hole 130elongated in a direction extending parallel to the longitudinal axis110. An axial length (of the elongated hole 130 is at least larger thana diameter of the first through fifth plate holes 112, 114, 116, 126,128 while a width of the elongated hole 130 may be equivalent to thediameter of the first through fifth plate holes 112, 114, 116, 126, 128.In a preferred embodiment, the first through fifth plate holes 112, 114,116, 126, 128 are 1.5 mm variable angle holes. However, in anotherembodiment, one or more of the first through fifth plate holes 112, 114,116, 126, 128 may be formed as standard locking holes having a diameterof 1.3 mm. Still further, it is noted that any other diameter of theholes may be used without deviating from the scope of the invention toconform to the requirements of a particular procedure. As will bedescribed in greater detail below with respect to the exemplary method,the elongated hole 130 permits a surgeon or other user to slide the boneplate 100 over the bone within a predetermined range (i.e.,corresponding to a length of the elongated hole 130) prior to lockingthe bone plate 100 in place. In one embodiment, the elongated hole 130allows for 3 mm. of movement along the longitudinal axis 110 while alsopermitting rotation of the bone plate 100 therearound, as will also bedescribed in greater detail later. The exemplary elongated plate hole130 extends orthogonally through the bone plate from the upper surface120 to the bone contacting surface 118. The elongated hole 130 bypassesthe need for a guidewire to position the bone plate 100 over the bone.Rather, since the bone plate 100 is adjustable relative to a bone screwinserted through the elongated hole 130, a surgeon or other user may usethe elongated hole 130 itself as a guide when positioning the bone plate100 over the bone.

The fourth and fifth holes 126, 128 are axially aligned along the shaft108 while the elongated hole 130 is offset relative to the longitudinalaxis 110 toward the first lateral wall 132. The offset position of theelongated hole 130 increases the stability of the connection between thebone plate 100 and the target bone. The bone-contacting surface 118 ofthe shaft 108 is curved along the longitudinal axis 110 to conform tothe substantially cylindrical shape of the target portion of the boneover which the shaft 108 will be seated. In one embodiment, the lengthof the shaft 108 may include a single uniform curvature. In anotherembodiment, the bone contacting surface 118 of the shaft 108 may includea plurality of curves selected to ensure that the shaft 108 is seatedflush over the bone.

The shaft 108 also includes a plurality of first webbed portions 146extending along the first lateral wall 132 between each of the holes116, 126, 130, 128 and a plurality of second webbed portions 148extending along the second lateral wall 134 between each of the holes116, 126, 130, 128. The first and second webbed portions 146, 148 areformed as notches extending into the width of the bone plate 100reducing a profile thereof while maintaining the structural integrity ofthe bone plate 100. The first and second webbed portions 146, 148 aswell as the notches 140, 142, 144 are sized to maintain a minimumdesired clearance remains around the boundary of each of the plate holesof the bone plate 100. An outer periphery of the bone plate 100 mayinclude a rounded taper to further reduce the profile as would beunderstood by those skilled in the art.

In accordance with an exemplary method according to the invention, thebone plate 100 is positioned over a target portion of a bone 10.Specifically, the bone plate 100 is positioned over a lateral or medialside of the bone adjacent the phalangeal head, as shown in FIG. 9. Thesurgeon or other user approximates the desired position of the boneplate 100 over the bone 10. A cortex screw (not shown) is then insertedthrough the elongated hole 130 and into the bone 10 to a first depthsufficient to hold the bone plate 100 over the bone 10 while stillpermitting movement of the bone plate 100 relative to the bone 10. Thebone plate 100 is then slid axially along the length of the elongatedhole 130 and/or rotated about the cortex screw (not shown) until a finaltarget position has been achieved. The exemplary system and methodaccording to the invention bypasses the need for pre-drilling holes inthe bone. Rather, once the target position has been achieved, bore holesare drilled through any of the first, second, third, fourth and fifthplate holes 112, 114, 116, 126, 128 and into the bone 10. In contrast,present bone fixation systems require the insertion of a guidewire intothe bone prior to the placement of the bone plate over the bone, thusrequiring that a final position of the bone plate 100 be selected priorto the placement of the bone plate over the bone. This method may leadto reduced accuracy in placement, especially in the fixation ofphalangeal bones where even the smallest deviation, (e.g., inmillimeters) from a correct position may lead to less than optimumfixation. The exemplary bone plate 100, on the other hand, permitsadjustment of the position of the bone plate 100 even after the boneplate 100 has been initially secured to the bone, thereby ensuring thatthe final position of the bone plate 100 captures all fragments of thebone 10 while avoiding interference with ligaments, tendons or othertissue.

Once the bone plate 100 has been moved to the target position, aguidewire (not shown) is inserted in the center of a condyle of the bone10 within the first notch 140. The guidewire 140 serves to retain thebone plate 100 in the target configuration while bone screws areinserted into plate holes thereof. In another embodiment, this optionalstep may be omitted. A bone screw (not shown) is then inserted into thefirst plate hole 112, followed by a bone screw (not shown) in the secondplate hole 114. Bone screws (not shown) may then be inserted into any ofthe third, fourth and fifth plate holes 116, 126, 128 depending on thefracture pattern. The bone screw inserted into the elongated plate hole130 may be tightened to firmly engage the bone plate 100.

The exemplary bone plate 100 depicted in FIGS. 1-10 is configured forplacement in right hand bones. For fixation of bones of the left hand, abone plate 100′ may be used, as shown in FIG. 11. The bone plate 100′ isformed substantially similarly to the bone plate 100, with like elementsreferenced with like reference numerals, except as noted below. Firstand second lateral side walls 132′, 134′ are reversed in the bone plate100′, resulting in a mirror-image of the bone plate 100.

FIGS. 12-14 depict a bone plate 200 according to another embodiment ofthe invention. The bone plate 200 is formed substantially similar to thebone plate 100, wherein like elements have been referenced with likereference numerals, except as noted below. However, whereas the head 104and shaft 108 of bone plate 100 are substantially aligned along thelongitudinal axis 110, the bone plate 200 is configured so that a head204 thereof is angled relative to a shaft 208 thereof. Specifically, aneck region 205 extending between the head 204 and shaft the 208 extendsalong a longitudinal axis 207 angled relative to a longitudinal axis 210of the shaft 208. The angle of the longitudinal axis 207 relative to thelongitudinal axis 210 is selected so that no portion of the head 204intersects the longitudinal axis 210. It is noted, however, that anyother angle may be selected without deviating from the scope of theinvention. The exemplary bone plate 200 is selected to span multiplesurfaces of a target bone, thereby increasing the strength of theconnection between the bone plate 200 and the fragments of the targetbone. For example, the head 204 may be seated on a lateral surface ofthe bone while the shaft 208 extends from the lateral surface to adorsal surface of the bone. A curvature of a bone-contacting surface 218of the bone plate 200 is selected to conform to the desired placement ofthe bone plate 200. The bone plate 200 is selected for placement inbones of the right hand. FIG. 14 depicts a bone plate 200′ formed forinsertion on bones of the left hand. As with the bone plates 100, 100′,the bone plate 200′ is a mirror-image of the bone plate 200.

It will be appreciated by those skilled in the art that variousmodifications and alterations of the disclosed embodiments may be madewithout departing from the broad scope of the invention. Some of thesehave been discussed above and others will be apparent to those skilledin the art.

What is claimed is:
 1. A bone plate sized and shaped for fixation to aphalangeal bone, comprising: a head extending from a first end to asecond end and having first, second and third fixation element holesextending therethrough and arranged in a triangular configuration on thehead, an outer wall of the head having a triangular shape correspondingto the triangular configuration, a bone contacting surface of the headbeing contoured to conform to the anatomy of a lateral surface of aphalangeal head; and a shaft extending from the head, the shaftincluding fourth and fifth fixation element holes separated from oneanother by an elongated fixation element hole elongated in a directionparallel to a longitudinal axis of the shaft.
 2. The bone plate of claim1, wherein the triangular shape of the head includes a first corner atthe first end, a second corner along a first side wall of the bone plateand a third corner at a neck connecting the head to the shaft.
 3. Thebone plate of claim 2, wherein the first and second corners of the headare curved downward toward the bone.
 4. The bone plate of claim 2,wherein the head further comprises a first notch on the first endbetween the first and second fixation element holes, the first notchformed as an indentation on an outer wall of the bone plate sized andshaped to accommodate a guidewire when the plate is fixed to thephalangeal bone in a desired position.
 5. The bone plate of claim 4,wherein the head further comprises a second notch on a second side wallof the bone plate between the first and third fixation element holes anda third notch on the first side wall between the second and thirdfixation element holes.
 6. The bone plate of claim 2, wherein the neckis formed with a reduced diameter relative to adjacent portions of thehead and shaft.
 7. The bone plate of claim 6, wherein the neck is angledso that a longitudinal axis of the head is angled relative to thelongitudinal axis of the shaft.
 8. The bone plate of claim 2, whereinthe elongated fixation element hole is offset from the longitudinal axisof the shaft.
 9. The bone plate of claim 8, wherein the elongatedfixation element hole is offset toward the first side wall of the boneplate.
 10. The bone plate of claim 1, wherein the fourth and fifthfixation element holes are symmetric with respect to the longitudinalaxis of the shaft.
 11. The bone plate of claim 1, wherein the shaftincludes plurality of fourth notches formed in the first and second sidewalls, the fourth notches defining reduced width regions of the shaft.12. The bone plate of claim 11, wherein the fourth notches are locatedalong the length of the shaft between adjacent ones of the fourthfixation element hole, the elongated hole and the fifth fixation elementhole.
 13. The bone plate of claim 1, further comprising a tapered regionextending around a periphery of the bone plate to reduce a profilethereof.
 14. The bone plate of claim 1, wherein trajectories of thefirst, second and third fixation element holes are oriented to divergeaway from one another.
 15. The bone plate of claim 1, whereintrajectories of the fourth and fifth fixation element holes are orientedto extend toward a center of the bone.
 16. A method for bone fixation,comprising: positioning a bone plate over a lateral surface of aphalangeal bone so a head of the bone plate is seated over a phalangealhead, the bone plate extending from a first end having the head to asecond end having a shaft, the head of the bone plate including first,second and third fixation element holes extending therethrough andarranged in a triangular configuration on the head, an outer wall of thehead having a triangular shape corresponding to the triangularconfiguration, a bone contacting surface of the head being contoured toconform to the anatomy of the lateral surface of the phalangeal head,the bone plate including a shaft extending from the head; inserting afirst fixation element into an elongated fixation element hole extendingthrough the shaft, wherein the elongated fixation element hole iselongated in a direction parallel to a longitudinal axis of the shaft;sliding the bone plate over the phalangeal bone within a range of motionlimited by a length of the elongated fixation element hole to a desiredlocation over a lateral surface of the phalangeal bone; inserting asecond fixation element into the first fixation element hole; andinserting a third fixation element into the second fixation element holeto lock the bone plate over the phalanx.
 17. The method of claim 16,further comprising the step of inserting a guidewire into the phalangealhead so that the guidewire is received in a notch on the first endbetween the first and second fixation element holes, the guidewiremaintaining a position of the bone plate over the phalangeal bone priorto insertion of second and third fixation elements thereinto.
 18. Themethod of claim 16, further comprising the step of rotating the boneplate about the first fixation element to the desired location prior toinsertion of second and third fixation elements thereinto.